M. es (Claparède and Lachmann, 1858) Kahl, 1930-5: (Syn. Metopus sigmoides Claparède and Lachmann, 1858 ) Cell body elongate, 160 μm long, anterior large and twisted to the left, slightly protruded from the body, AZM curving down to the equatorial region, posterior narrowed with a blunt end, no caudal cilia, a single macronucleus ovoid, a single contractile vacuole terminal (Carey, 1992).